Patient-specific devices and methods for anatomic ligament reconstruction or repair

ABSTRACT

Patient-specific devices are formed from electronic image data taken preoperatively from a patient and used to create a 3-D model of the patient&#39;s knee joint. The anatomic location of the anatomic insertion points of the ACL, and hence the anatomic location of a bone tunnel for housing a ligament graft, are then identified on the 3-D model. The anatomic location of the ACL footprint is used to create a 3-D-printed template with apertures corresponding to the footprint of the ACL (or its bundles). The template can be attached to a reusable handle of an existing drill guide for drilling the bone tunnel corresponding to the footprint of the ACL. In other examples, the anatomic location of the ACL footprint is registered and mapped onto a real-time computer display of the patient&#39;s bone during the ligament reconstruction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. ProvisionalApplication No. 62/977,833, filed Feb. 18, 2020, entitledPATIENT-SPECIFIC DEVICES AND METHODS FOR ANATOMIC LIGAMENTRECONSTRUCTION OR REPAIR, the entire contents of which are incorporatedherein by reference for all purposes.

FIELD

The present disclosure relates to devices and methods for surgicalreconstruction or repair of joint ligaments using patient-specific data.

BACKGROUND

A ligament, such as an anterior cruciate ligament (ACL), that hasruptured and is non-repairable, is generally replaced arthroscopicallyby a tissue graft. The replacement graft is usually implanted bysecuring one end of the graft in a bone tunnel formed within the femur,and securing the other end of the graft in a bone tunnel formed in thetibia. In many cases, the function of the reconstructed knee joint isdependent on the anatomic location of the tunnel drilled through thefemur and/or the tibia to house the tissue graft. For example, graftsplaced too far anteriorly on the femur are reportedly a common cause offailure in ACL reconstruction. If the tunnel location is placed onanatomic footprint of the native ACL, the physiological outcome of theoperation is greatly improved and reduces the need for a potentialrevision ACL reconstruction. However, accurate determination of the ACLfootprint during arthroscopic ligament reconstruction can bechallenging, especially for more junior surgeons. The location of theACL footprint may vary among patients based on gender, height and otherfeatures, while many current devices used to predict the ACL footprintare based on an average footprint size and location and used for allpatients. These devices could create up to a few millimeters of error inpredicting the native ACL footprint. Therefore, it is desirable to havedevices and methods for more accurate placement of the femoral and/ortibial tunnels to reduce the incidence of graft failure and/or long-termdegeneration after ligament reconstruction.

SUMMARY

Described herein patient-specific devices and methods designed toeliminate misplacement of an ACL graft tunnel relative to the native ACLinsertion points on the corresponding bone. Initially, electronic imagedata is taken preoperatively from the patient and used to create a 3-Dmodel of the patient's knee joint. The location of the anatomicinsertion points of the ACL, and hence the location of the bone tunnelfor housing a ligament graft, are then identified on the 3-D model. Insome examples, the location of the ACL footprint is used to create a 3-Dprinted template with apertures corresponding to the footprint of theACL (or its bundles). The template can be attached to a reusable handleof an existing drill guide for drilling the bone tunnel corresponding tothe footprint of the ACL. In other examples, the location of the ACLfootprint is registered and mapped onto a real-time computer display ofthe patient's bone during the ligament reconstruction. The surgeon canuse the display as a reference to decide the final location of the ACLfootprint before placing the graft tunnel. Advantageously, both methodsprovide the surgeon with patient-specific data for accuratelydetermining the location of a bone tunnel for housing a ligament grafton the femoral and/or tibial bones.

Further examples of the methods and devices of this disclosure mayinclude one or more of the following, in any suitable combination.

In examples, a method of making a surgical instrument of this disclosureincludes obtaining electronic image data of a joint, including at leastone bone, of a patient. Using the electronic image data, a 3-D model ofthe at least one bone is created. Using the 3-D model, at least oneanatomic insertion point of a ligament on the at least one bone isdetermined. Based on the at least one anatomic insertion point, ananatomic location of a tunnel through the at least one bone isdetermined for housing a graft. Based on the anatomic location of thetunnel, a template is created for attachment to a surgical guide. Thetemplate includes at least one aperture for directing a drill insertedthrough the surgical guide to drill the tunnel at the anatomic location.

In further examples, determining the at least one anatomic insertionpoint of the ligament includes determining the at least one anatomicinsertion point on a series of 2-dimensional images obtained from theelectronic image data. In examples, determining the at least oneanatomic insertion point of the ligament includes determining the atleast one anatomic insertion point on the 3-D model using the at leastone anatomic insertion point on the series of 2-dimensional images. Inexamples, the at least one bone is a femur or a tibia, and the ligamentis an anterior cruciate ligament or at least one of an anteromedial orposterolateral bundle. In examples, creating the template comprisescreating the template by additive manufacturing. In examples, a surfaceof the template comprises retention features for securing the templateto the at least one bone. In examples, the template is comprised ofplastic. In examples, the electronic image data is obtained usingmagnetic resonance imaging (MRI).

Examples of a template for attachment to a surgical guide of thisdisclosure include a template formed by the method of obtainingelectronic image data of a joint, including at least one bone, of apatient; using the electronic image data, creating a 3-D model of the atleast one bone; using the 3-D model, determining at least one anatomicinsertion point of a ligament on the at least one bone; based on the atleast one anatomic insertion point, determining an anatomic location ofa tunnel through the at least one bone for housing a graft; and, basedon the anatomic location of the tunnel, creating the template forattachment to the surgical guide.

Examples of a method for simulating reconstructive surgery of a ligamentusing electronic image data of this disclosure, the method at leastpartially executed by a processor within a computing system, includeobtaining electronic image data of a joint, including at least one bone,of a patient; creating a 3-D model of the at least one bone using theelectronic image data; determining at least one anatomic insertion pointof a ligament on the at least one bone based on the 3-D model;determining an anatomic location of a tunnel through the at least onebone for housing a graft based on the at least one anatomic insertionpoint; and mapping and superimposing, using augmented reality, theanatomic location of the tunnel on a real-time image of the at least onebone on a display device.

In further examples, determining the at least one anatomic insertionpoint of the ligament comprises determining the at least one anatomicinsertion point on a series of 2-dimensional images obtained from theelectronic image data. In examples, determining the at least oneanatomic insertion point of the ligament comprises determining the atleast one anatomic insertion point on the 3-D model using the at leastone anatomic insertion point on the series of 2-dimensional images. Inexamples, the at least one bone is a femur or a tibia and the ligamentis an anterior cruciate ligament or at least one of an anteromedial or aposterolateral bundle. In examples, the electronic image data isobtained using magnetic resonance imaging (MRI). In examples,superimposing the anatomic location of the tunnel on the real-time imageof the at least one bone comprises superimposing a silhouette of the atleast one anatomic insertion point on a real-time image of a femoralcondyle. In examples, the method further includes mapping the at leastone anatomic insertion point onto the 3-D model of the at least one boneand displaying the 3-D model of the at least one bone on a portion ofthe display device.

These and other features and advantages is apparent from a reading ofthe following detailed description and a review of the associateddrawings. It is to be understood that both the foregoing generaldescription and the following detailed description are explanatory onlyand are not restrictive of aspects as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is more fully understood by reference to the detaileddescription, in conjunction with the following figures, wherein:

FIG. 1 is a schematic illustration of a patient-specific surgicalinstrument of this disclosure;

FIG. 2 is an illustration of a knee joint of a patient in atwo-dimensional view;

FIG. 3 is an illustration of a 3-D model of the knee joint of thepatient;

FIGS. 4A-C are detailed illustrations of a patient-specific template foruse with the surgical instrument of this disclosure;

FIGS. 5A-C illustrate a method of superimposing images onto a real-timedisplay of a knee joint of a patient during a ligament reconstruction;and

FIGS. 6A and 6B illustrate another 3-D model of the femoral bone of aknee joint of the patient and its corresponding ligament insertionpoints.

DETAILED DESCRIPTION

In the description that follows, like components have been given thesame reference numerals, regardless of whether they are shown indifferent examples. To illustrate example(s) in a clear and concisemanner, the drawings may not necessarily be to scale and certainfeatures may be shown in somewhat schematic form. Features that aredescribed and/or illustrated with respect to one example may be used inthe same way or in a similar way in one or more other examples and/or incombination with or instead of the features of the other examples.

As used in the specification and claims, for the purposes of describingand defining the invention, the terms “about” and “substantially” areused to represent the inherent degree of uncertainty that may beattributed to any quantitative comparison, value, measurement, or otherrepresentation. The terms “about” and “substantially” are also usedherein to represent the degree by which a quantitative representationmay vary from a stated reference without resulting in a change in thebasic function of the subject matter at issue. “Comprise,” “include,”and/or plural forms of each are open ended and include the listed partsand can include additional parts that are not listed. “And/or” isopen-ended and includes one or more of the listed parts and combinationsof the listed parts.

Referring now to FIGS. 1-3, a surgical instrument 100 for ligamentrepair of this disclosure, as well as methods of making the instrument100 using patient-specific data, are illustrated. As shown in FIG. 1,the instrument 100 generally comprises a reusable guide 102 and anattachable template 104 with apertures 106 corresponding to thefootprint of the ACL. The apertures 106 may also correspond to thefootprints of the anteromedial (AM) bundle and the posterolateral (PL)bundle of the ACL, as further described below. Alternatively, it iscontemplated by this disclosure that the instrument 100 could bedesigned for the insertion of the posterior cruciate ligament (PCL) orother ligaments.

Still referring to FIG. 1, examples of the guide 102 can include ahousing 108 for retaining an insertion member 110. Examples of theinsertion member 110, known in the art as a “bullet,” have an aimer tip112 and an insertion knob 114 for directing a drill (not shown) insertedthrough the insertion member 110 along an insertion axis A to ananatomic insertion point at a surgical site, such as a bone tunnellocation on a femur. In examples, the housing 108 couples to an aimerarm 118 via a slot 120 for sliding movement therein, and may have an arcshape for arcuate movement. A guide arm 122 for attachment to thetemplate 104 of this disclosure couples to the aimer arm 118, and mayhave a hinged connection (not shown) for rotation of the guide arm 122and the template 104 in the plane defined by the aimer arm 118 and theinsertion member 110. The guide arm 122 may be straight, as shown, ormay be curved toward the insertion axis A. The apertures 106 in thetemplate 104 define the drilling footprint at the surgical site, thusproviding an indication of the diameter and anatomic location of theresulting bone tunnel, while the insertion axis A indicates the path ofthe bone tunnel through the apertures 106 in the template 104. Inexamples, a length of the guide arm 122 could be adjustable to ensurethat the insertion axis A passes through the desired apertures 106 onthe template 104. Other non-limiting examples of the guide 102 aredescribed in U.S. Pat. No. 9,078,675 to Smith & Nephew, Inc.,incorporated herein by reference in its entirety.

Turning now to FIG. 2, a knee joint 130 of a patient, including a femur132 and a tibia 134, is illustrated in a two-dimensional view.Initially, to form the surgical instrument 100 of FIG. 1, a series ofpre-operative, two-dimensional electronic images of the knee joint 130are created using a series of electronic image data. The electronicimage data may be derived from computed tomography (CT) or magneticresonance imaging (MRI). However, soft tissues and their correspondinginsertion points can generally be determined more accurately using MM.The series of 2-D images may include the two femoral condyles 132 a,b(FIG. 3) about 10-15 cm from the knee joint line. Once the images of theknee joint 130 are generated, the femoral ACL footprint 136 and thetibial ACL footprint 138 are identified on the series of 2-D images. Theanatomic footprints 136, 138 may be identified by their unique contouron the bone surface or by identifying ligament fiber remnants in theirrespective locations. Next, a 3-D model of the femur 132 and the tibia134 is created from the series of 2-D images. As shown in FIG. 3, the3-D anatomic locations of ACL footprints 136, 138 are then defined onthe 3-D bone model from the identified ACL footprints 136, 138 on the2-D images. The data obtained from the geometry of the ACL footprint(and potentially the geometry of the patient's lateral femoral condyle132 b) can then be used to create the patient-specific template 104 ofthis disclosure with specifications tailored to the patient's ligamentfootprints 136, 138 for use during the patient's ligament reconstructionprocedure.

Turning now to FIGS. 4A-C, examples of the patient specific template 104are shown in detailed views. The template 104 can be attached to acurrently available guide 102, such as the guide 102 of FIG. 1, and usedduring the ligament reconstruction. For example, the template 104 couldbe configured for a snap-fit to the guide 102. In examples, the template104 may be created using additive manufacturing (i.e., “3-D printing”)and is comprised of a plastic. Examples of the template 104 include anelongated, flattened body 105 including a wider, circular area 107 thatis slightly raised toward the insertion axis A (FIG. 1). A surface ofthe circular area 107 facing the insertion axis A may include spikes 124or other retention features for securing the template 104 to a surfaceof the bone. The circular area 107 also defines the apertures 106 a,b,c,corresponding to the footprints of the ACL or its bundles. The body 105,including the circular area 107, provide a low profile to facilitateinsertion between anatomical members. The body 105 of the template 104may be planar, as shown, or may be curved toward the insertion axis A. Alength of the template 104, as well as the size of and distance betweenthe apertures 106 a,b,c can vary based on the anatomy of the individualpatient. An end of the body 105 opposite the guide arm 122 comprises anend hook 126 angled toward the insertion axis A. When the end hook 126of the template 104 is placed behind the posterior wall of the patient'sfemoral notch and the guide 102 is held parallel to tibial plateau,aperture 106 b of the template 104 indicates the anatomic insertion ofthe ACL. Similarly, the apertures 106 a and 106 c indicate the anatomicinsertion of the AM/PL bundles, respectively. Once proper anatomicand/or functional positioning of the template 104 is achieved, theligament tunnel can be created using the guide 102.

In alternative examples, shown in FIGS. 5A-C, the femoral ACL footprint136 which was identified on the 3-D model of the patient's knee joint130 is registered and mapped onto a real-time image of the patient'sfemoral condyle 132 b during the ligament reconstruction. For example,using augmented reality (AR), a silhouette 140 of the ACL footprint 136can be shown on the computer display 142 of the arthroscopy tower 144overlapped on the real-time image of the femoral condyle 132 b, suchthat the silhouette 140 does not block the view of the surgeon 146. Thesilhouette 140 can provide the surgeon 148 with a reference point todecide the final anatomic location of the ACL footprint 136 beforeplacing the graft tunnel. The insertion areas of the ACL footprint 136can be presented in two modes and surgeon can switch between thesemodes. For example, the modes may include a single bundle mode for theACL (FIG. 5B) or a double bundle mode for the AM/PL bundles (FIG. 5C).The centroid 150 of each insertion area can be added to the view as aturn on/off option. Additionally, as shown in FIGS. 6A and 6B, theanatomic insertion points 152 can be mapped onto a 3-D model of thefemur 132 of the individual patient using augmented reality for anoverall visualization of the anatomic insertion points 152 and as anextra check point. The 3-D model can be displayed in a corner of thecomputer display 142.

One skilled in the art will realize the disclosure may be embodied inother specific forms without departing from the spirit or essentialcharacteristics thereof. The foregoing examples are therefore to beconsidered in all respects illustrative rather than limiting of thedisclosure described herein. Scope of the disclosure is thus indicatedby the appended claims, rather than by the foregoing description, andall changes that come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

1. A method of making a surgical instrument for ligamentreconstruction/repair, the method comprising: obtaining electronic imagedata of a joint, including at least one bone, of a patient; using theelectronic image data, creating a 3-D model of the at least one bone;using the 3-D model, determining at least one anatomic insertion pointof a ligament on the at least one bone; based on the at least oneanatomic insertion point, determining an anatomic location of a tunnelthrough the at least one bone for housing a graft; and based on theanatomic location of the tunnel, creating a template for attachment to asurgical guide, the template including at least one aperture fordirecting a drill inserted through the surgical guide to drill thetunnel at the anatomic location.
 2. The method of claim 1, whereindetermining the at least one anatomic insertion point of the ligamentcomprises determining the at least one anatomic insertion point on aseries of 2-dimensional images obtained from the electronic image data.3. The method of claim 2, wherein determining the at least one anatomicinsertion point of the ligament comprises determining the at least oneanatomic insertion point on the 3-D model using the at least oneanatomic insertion point on the series of 2-dimensional images.
 4. Themethod of claim 1, wherein the at least one bone is a femur or a tibia.5. The method of claim 1, wherein the ligament is an anterior cruciateligament.
 6. The method of claim 1, wherein the ligament is at least oneof an anteromedial or posterolateral bundle.
 7. The method of claim 1,wherein creating the template comprises creating the template byadditive manufacturing.
 8. The method of claim 1, wherein a surface ofthe template comprises retention features for securing the template tothe at least one bone.
 9. The method of claim 1, wherein the template iscomprised of plastic.
 10. The method of claim 1, wherein the electronicimage data is obtained using magnetic resonance imaging (MRI).
 11. Atemplate for attachment to a surgical guide formed by the method ofclaim
 1. 12. A method for simulating reconstructive surgery of aligament using electronic image data, the method at least partiallyexecuted by a processor within a computing system, the methodcomprising: obtaining electronic image data of a joint, including atleast one bone, of a patient; creating a 3-D model of the at least onebone using the electronic image data; determining at least one anatomicinsertion point of a ligament on the at least one bone based on the 3-Dmodel; determining an anatomic location of a tunnel through the at leastone bone for housing a graft based on the at least one anatomicinsertion point; and mapping and superimposing, using augmented reality,the anatomic location of the tunnel on a real-time image of the at leastone bone on a display device.
 13. The method of claim 12, whereindetermining the at least one anatomic insertion point of the ligamentcomprises determining the at least one anatomic insertion point on aseries of 2-dimensional images obtained from the electronic image data.14. The method of claim 12, wherein determining the at least oneanatomic insertion point of the ligament comprises determining the atleast one anatomic insertion point on the 3-D model using the at leastone anatomic insertion point on the series of 2-dimensional images. 15.The method of claim 12, wherein the at least one bone is a femur or atibia.
 16. The method of claim 12, wherein the ligament is an anteriorcruciate ligament.
 17. The method of claim 12, wherein the ligament isat least one of an anteromedial or a posterolateral bundle.
 18. Themethod of claim 12, wherein the electronic image data is obtained usingmagnetic resonance imaging (MRI).
 19. The method of claim 12, whereinsuperimposing the anatomic location of the tunnel on the real-time imageof the at least one bone comprises superimposing a silhouette of the atleast one anatomic insertion point on a real-time image of a femoralcondyle.
 20. The method of claim 12, further comprising: mapping the atleast one anatomic insertion point onto the 3-D model of the at leastone bone; and displaying the 3-D model of the at least one bone on aportion of the display device.